Accrued Liabilities (Accrued Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accrued Liabilities [Abstract]
Employee costs	$ 6,198	$ 8,878
Lease operating expenses	6,114	6,405
Capital expenditures	5,212	3,461
Taxes	3,396	2,324
Interest payable	300	884
Legal settlement	0	2,070
Other	1,888	1,182
Total accrued liabilities	$ 23,108	$ 25,204